#include <iostream>
#include <cstring>
using namespace std;
constexpr int MAXN = 100;
int memory[MAXN];
int fib(int);
int main() {
    memset(memory, -1, sizeof memory);
    int n;
    cin >> n;
    cout << "result is " << fib(n) << endl;
}

int fib(int n) {
    if (memory[n] != -1) return memory[n];
    return n <= 1 ? n : memory[n] = fib(n - 1) + fib(n - 2);
    
}